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Updated: April 30, 2025
The following table gives the results of certain experiments made early in 1879, with a Gramme machine, by an able physicist, M Hagenbach, Professor at the University at Basle, and kindly furnished by him to the author: Revolutions per minute 935 919.5 900.5 893 Total resistance in Siemens' units 2.55 3.82 4.94 6.06
At Gratz he saw and operated a Gramme machine for the first time, and was so struck with the objections to the use of commutators and brushes that he made up his mind there and then to remedy that defect in dynamo-electric machines. In the second year of his course he abandoned the intention of becoming a teacher and took up the engineering curriculum.
This dynamo, as is well known, differs from those of Gramme and Paccinotti chiefly in the longitudinal winding of the armature, and it is unnecessary to describe it here. It has been adapted by its inventors to all kinds of electrical work, electrotyping, telegraphy, electric lighting, and the propulsion of vehicles.
Elihu Thomson, investigated the merits of existing dynamos and reported as to the best of them: "The Gramme machine is the most economical as a means of converting motive force into electricity; it utilizes in the arc from 38 to 41 per cent. of the motive work produced, after deduction is made for friction and the resistance of the air."
For instance one gramme iron, which has passed through a metal sieve with holes half a millimeter in diameter, is placed in a beaker 125 mm. in height and 60 mm. in diameter, and has added to it twenty cubic centimeters of hydrochloric acid of 1.12 specific gravity, which, with a well-fitting glass cover, is boiled for half an hour, in order that the combined carbon may be driven off in the shape of gas.
If, for instance, one cubic centimeter chameleon solution corresponds to 0.01 gramme iron, the figure for manganese is 0.01 x 0.295 = 0.00295 gramme per cubic centimeter.
The binoxide of commerce, as taken from the mine, is well sampled, powdered, and dried at 100 deg.C. 0.5 gramme of this is taken and placed in a 250 c.c. flask; in analysis the binoxide on the filter, from the treatments noted under separation is thoroughly washed with warm water; it is then washed down in a flask, as above, after breaking the filter paper; sufficient water is added to one-third fill the flask, and about twice the approximate weight of the binoxide in the flask of oxalate of potassa; these are agitated together.
The solid mass of elaidin formed was of a darker color than that from olive, almond, and tea oil, but closely resembled that from rape oil. Free Acidity. This was estimated as above described. 100 grammes of oil would require 0.125 gramme caustic potash. Saponification of the Oil.
It is possible, by considerations analogous to those set forth above in other cases, to arrive at an idea of the total number of particles per second expelled by one gramme of radium; Professor Rutherford in his most recent evaluation finds that this number approaches 2.5 x 10^ . By calculating from the atomic weight the number of atoms probably contained in this gramme of radium, and supposing each particle liberated to correspond to the destruction of one atom, it is found that one half of the radium should disappear in 1280 years; and from this we may conceive that it has not yet been possible to discover any sensible loss of weight.
They are expressed in units of electricity, the unit being the quantity of electricity which, acting upon a similar unit at a distance of one centimeter, produces a repulsion equal to one gramme: Volta pile 0.03415 open circuit.
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